We completed a study on the magnetic effect of a fast relaxer, DyCl3, as the DyCl3 approaches an immobilized free-radical signal found in tissue. A practical application of this work for the immobilized free-radical project is the enhancement of the signal-to-noise ratio at high microwave powers. Because the distance of closest approach for DyCl3 in tissue equaled that of metal to galvinoxyl in alcohol, we concluded that the free radical remains in a hydrophylic region, well exposed to metal complexes. The spectrometer for 8-multi-displays (absorption and dispersion, 1st and 2nd harmonic, in-phase and in-quadrature) is in operation and computer simulation of these 8-multi-displays will be available. A cavity for taking difference spectra between 8.4 and 9.6 GHz has been developed. Development of an S-band spectrometer will be completed by 1978. We plan to use this study to characterize immobilized free radicals found in tumor tissue. The methods developed should be applicable to broader fields concerning free radicals in enzymes and in irradiation damage, as well as in cancer.